You can definitely follow their account, it's @lfdi_pressestelle , just go there and click "follow" 😁
After you've followed them, the videos they upload from that moment onward should start appearing embedded in posts on your Mastodon timeline.
I've never caught a PeerTube livestream on my timeline but as far as I know it should embed the same way as prerecorded videos? (At the very least, the catchup version should be embedded.)